Method of cooling liquids



Sept. 1, 1964 T. PORTER, JR 3,146,603

METHOD OF COOLING uqums.

F iled Nov. 29, 1962 INVENTOR: THOMAS PORTER, JUNIOR ATTORNEY.

United States Patent 3,146,603 METHOD OF COOLING LIQUIDS Thomas Porter, Jr., Flixton, Urmston, Manchester, England, assignor to T. Porter & C0. (Salford) Limited, Manchester, England, a British company Filed Nov. 29, 1962, Ser. No. 240,886 1 Claim. ((31. 62-98) This invention is concerned with a device for the cooling of liquids, in particular liquid beverages, and relates to the type of device known in the hotel and catering trades as an in-line cooler which is, disposed in a conduit between a bulk supply, such as a barrel or tank, and a draw-off tap or dispenser.

One object of the invention is to provide a simple form of in-line cooler in which the heat-extraction ratio "is automatically variable in response to the heat load imposed upon it by the drawing-off of the liquid being cooled. Another object of the invention is to provide a simple construction of in-line cooler which can be produced rapidly and at relatively low cost and which can be quickly dismantled for cleaning out the beverage circuit and as quickly re-assembled without interfering with the refrigerant circuit. In its preferred forms, the principal parts are symmetrical and co-axial, being generally identical in shape but of different size, and they are adapted for easy manufacture and assembly.

According to this invention, a refrigerant circuit of the condenser-evaporator type is characterised by an evapo rator arranged whereby the liquid to be cooled can flow thereover and which is of such form interiorly that there is a narrow space in which bubbles, formed by the boiling of the coolant fluid due to heat transfer from the said liquid, collect before complete evaporation, said narrow space providing an increased area for evaporation of the coolant and consequent increased heat extraction. The extent to which bubbles will collect within such increased area will depend upon the degree of the boiling of the coolant, which itself will depend on the heat load imposed on the coolant by the liquid being refrigerated.

In an apparatus according to the invention, the improved in-line cooler provides adjacent conduits or passages, one for the liquid to be cooled and the other constituting an evaporator, this latter containing the liquid coolant up to a controlled level and being of a narrow width such that, upon the boiling of the coolant, bubbles will collect in it above said level and create an increased area for heat exchange between the two conduits or passages.

In the preferred forms of the invention, the apparatus is made so that said conduits or passages are annular and concentric. This not only simplifies the manufacture of the parts to be assembled together, but also gives an increased area (cylindrical area) for heat exchange within a given total volume.

According to a further feature of the invention, the conduit for the liquid to be cooled lies between inner and outer shells or housings, the outer one of which is held in place by quick-release securing means so that it may be quickly removed for the cleaning of the beverage conduit. This outer shell is preferably flanged exteriorly for releasable connection to a base plate and the said inner shell is permanently connected to the base plate. A third and innermost shell, open at the top, is secured to the base at its bottom end and encloses an escape means for the evaporated coolant.

An apparatus according to the invention may therefore comprise a central, open-topped chamber having means for controlling the level of a liquid coolant therewithin, an intermediate closed-ended chamber slightly larger than and surrounding said open-topped chamber, there being small holes in the dividing wall between these 3,146,603 Patented Sept. 1, 1964 "ice two chambers so that coolant in the said intermediate chamber will be at the same level as in the central chamber. There is also an outer chamber providing a flow conduit for the liquid to be cooled, preferably with an inlet port at or near the lower end and an outlet port at or near the upper end, for example in the top wall. The parts will be made as far as possible of stainless steel or other non-corrosive, non-toxic material, and it is envisaged that for practical uses the cooler will be mounted on a base alongside a normal refrigerant apparatus including compressor and motor.

In the accompanying drawing, a representative example of apparatus according to the invention is illustrated, the single figure being a view in vertical diametral section. The apparatus is circular in plan.

As shown, there is a hollow metal base plate 1 to an upstanding peripheral flange 2 of which is welded the lower end of an open-ended metal cylinder 3. This cylinder 3 is apertured at one or more places 4 near the lower end, the apertures being of relatively small size. The cylinder 3 is fed with a volatile liquid coolant 5 through a capillary tube 6, the coolant being fed to pipe 6 by a condenser (not shown) which forms part of a conventional refrigerating system shown schematically in the drawing and identified by the legend Refrigerating System. A ball-float valve or other float control means 6 is disposed at the upper end of tube 6 for regulating the level of liquid coolant 5. In order to remove any oil which might collect at the bottom of cylinder 3, say from particles of lubricant carried over from the compressor, an oil-extraction pipe 7 is provided. The pipes 6 and 7 leave the base plate 1 through a tunnel formation 1 Surrounding cylinder 3 is a co-axial cylindrical housing 8, closed at the top, and the bottom end of which is welded to a peripheral face 9. Base plate 1, cylinder 3 and housing 8 are concentric and are of only a small difference in diameter so that there is a narrow annular space10 between them into which, because of the said aperture 4 in the inner wall 3, the liquid coolant 5 assumes in chamber 10 the level controlled by the said control means 6' in the control chamber 3. Extending upwardly through the base plate 1, within the inner chamber 3, is a vent pipe 11 leading to the compressor (not shown) of the Refrigerating System.

Surrounding and concentric with the parts so far described is a third and outer casing 12, also closed at the top and having an external peripheral flange 13 at the bottom. This flange 13 is adapted for securing to the base plate 1 detachably by a quick-release nut 14, and there is provided below the flange a resilient sealing ring 15. The parts are shown in the drawing in an intermediate stage of assembly, before the screwing down of the nut 14. The broken lines 12 indicate the position of the top of the housing 12 when fully assembled. There is an inlet port 16 near the lower end of the outer shell 12 and the top end of that shell is fitted with a connecting device 17 for a conduit leading to a dispenser or tap at a remote place. In some cases, a dispenser tap could be mounted directly at the top of housing 12. The annular space 18 between the shells 8 and 12 provides a cooling zone for liquid flowing between the inlet 16 and outlet 17.

The innermost annular space 10 is of such radial width that, when the coolant 5 at the bottom of that space begins to boil because of heat applied to it from the liquid to be cooled in the outer annular space 18, the coolant forms bubbles which, as shown at 19, collect in such annular space, in contact with the walls 3 and 8 defining the space, and the bubbles build up as a wall to a greater or less height before their complete evaporation, this height being dependent on the intensity of the boiling. This wall of bubbles 19 therefore produces a variable heat-exchange surface and the arrangement is such that, the greater the 3 degree of cooling required in the outermost chamber 18, the greater the intensity of boiling of the coolant 5, and therefore the higher the wall of bubbles 19 in the said intermediate annular space 10.

It will be seen therefore that there is an automatic regulation of the heat-exchange ratio, in proportion to the heat load imposed upon the cooler by the liquid being drawn off.

As the coolant liquid evaporates in the said intermediate annular space 10, it is drawn off from the top of the central chamber through the said vent pipe 11 into the compressor of the Refrigerating System and any liquid coolant that may be carried over into the central chamber with the evaporated gas falls into the coolant 5 in the well at the bottom of said chamber, and is used again in the refrigerant circuit.

The apparatus may be provided with an automatic cutoff switch for stopping the compressor or motor in the event of the temperature and/or pressure in the evaporator space falling below a predetermined minimum, and there may be means for regulating or adjusting this minimum according to circumstances prevailing at the time.

What I claim is:

In a method of coling liquids employing a refrigerant circuit of the condenser-evaporator type and including an open-topped liquid coolant chamber member for containing a liquid coolant circumscribed by a concentric closed-ended housing defining a narrow annular space between the walls of the liquid coolant chamber member and the closed-ended housing with the liquid coolant chamber member and the narrow annular space being intercommunicating, and an outer casing circumscribing the housing and defining a narrow annular cooling zone for the liquid to be cooled between the walls of the closedended housing and the outer casing, the steps comprising, collecting a wall of generated bubbles within the narrow annular space between the walls of the liquid coolant chamber and the closed-ended housing within the liquid cooling chamber upwardly of the level of the coolant fluid as controlled by a level control means preliminary to complete evaporation with the area of a heat exchange surface between the two chambers being automatically variable in dependence upon the heat load according to the contacting of the heat exchange surface by the generated bubbles with the extent of the heat exchange surface automatically increasing with any increase in the degree of cooling required by the liquid to-be cooled and decreasing with any decrease in the degree of cooling required by the liquid to be cooled.

References Cited in the file of this patent UNITED STATES PATENTS 1,911,042 Steenstrup May 23, 1933 2,517,773 Doughty Aug. 8, 1950 2,526,526 Yuza Oct. 17, 1950 2,532,328 Penning Dec. 5, 1950 2,555,682 Daun June 5, 1951 

